The guy does NOT need to quote he is relatively high ranking in the labour party which advocates comprehensive schools as being the best and most fair for children. Actions speak a dam site more than a politicians words.
But unless he's personally said he's against schools like Roedean he's not a hypocrite. He's just a member of a party where he agrees with most of the policies but not all of them. That's common right across the piece. The Tories cannot agree on Brexit (and neither can Labour btw) and have had a number of different education policies over the years. The idea that you join a party and believe every word it says just reinforces terrible legislation and partisan ideas for the sake of it. It's perfectly possible to be a Labour member and send your child to private school, just as it's perfectly possible (just about) to be on the centre of the party and fighting Corbynism from within - that's what Peter Kyle does.
Yet there's a whole thread full of people that presume to know that his private and public view points are different!